Evaluación de la distribución del caudal específico en aliviaderos escalonados sin cajeros laterales

Abstract

Traditionally the construction of stepped spillways in roller compacted concrete dams (RCC) is characterized by the presence of sidewalls that imposes a constant width along the spillway and guides the flow from the crest to the toe. These sidewalls imply significant time and cost of execution that could be considerably reduced. In the specialized literature there is a comprehensive description of the hydraulic behavior of stepped chutes with sidewalls and besides that recently few examples of stepped spillways designed without sidewalls have been found no formal investigation defines the hydraulic behavior in this condition. In this context arises the ALIVESCA with the objective of characterizing the hydraulic behavior of stepped spillways without sidewalls in RCC dams by physical modeling. The model located in Flumen Institute's laboratories (UPC), operates under the Froude similarity. It was constructed representing a 75 m dam height, 1.20 m step height, 0.8 slope and 45 m dam width (scale 1:15). In this article, the decrease of the specific discharge along and across the chute due to the flow lateral expansion is defined. The variables that determine such decrease are: the specific discharge at the entrance and the position (height) considered. Thus, an adjustment is proposed to predict the flow distribution in terms of these variables by mass conservation defined using flow gauging and image digital analysis.